octo-deno/lib/random/random.js

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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
var random = { // eslint-disable-line no-unused-vars
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seed: null,
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twister: null,
/**
* Must be called before any other methods can be called to initialize MersenneTwister.
* @param {number|null|undefined} seed Value to initialize MersenneTwister.
*/
init: function (seed) {
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if (seed === null || seed === undefined) {
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this.seed = new Date().getTime()
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}
this.twister = new MersenneTwister()
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this.twister.seed(this.seed)
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},
number: function (limit) {
// Returns an integer in [0, limit). Uniform distribution.
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if (limit === 0) {
return limit
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}
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if (limit === null || limit === undefined) {
limit = 0xffffffff
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}
let x = (0x100000000 / limit) >>> 0
let y = (x * limit) >>> 0
let r
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do {
r = this.twister.int32()
} while (y && r >= y) // eslint-disable-line no-unmodified-loop-condition
return (r / x) >>> 0
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},
float: function () {
// Returns a float in [0, 1). Uniform distribution.
return this.twister.real2()
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},
range: function (start, limit) {
// Returns an integer in [start, limit]. Uniform distribution.
if (isNaN(start) || isNaN(limit)) {
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logger.traceback()
throw new TypeError('random.range() received a non number type: \'' + start + '\', \'' + limit + '\')')
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}
return this.number(limit - start + 1) + start
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},
ludOneTo: function (limit) {
// Returns a float in [1, limit]. The logarithm has uniform distribution.
return Math.exp(this.float() * Math.log(limit))
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},
item: function (list) {
if (list === undefined || typeof list === 'string' || list.length === undefined) {
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logger.traceback()
throw new TypeError('random.item() received an invalid object: \'' + list + '\'')
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}
return list[this.number(list.length)]
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},
key: function (obj) {
let list = []
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for (let i in obj) {
list.push(i)
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}
return this.item(list)
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},
bool: function () {
return this.item([true, false])
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},
pick: function (obj) {
if (typeof obj === 'function') {
return obj()
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}
if (Array.isArray(obj)) {
return this.pick(this.item(obj))
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}
return obj
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},
chance: function (limit) {
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if (limit === null || limit === undefined) {
limit = 2
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}
if (isNaN(limit)) {
logger.traceback()
throw new TypeError('random.chance() received a non number type: \'' + limit + '\'')
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}
return this.number(limit) === 1
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},
choose: function (list, flat) {
if (!(Array.isArray(list))) {
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logger.traceback()
throw new TypeError('random.choose() received a non-array type: \'' + list + '\'')
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}
let total = 0
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for (let i = 0; i < list.length; i++) {
total += list[i][0]
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}
let n = this.number(total)
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for (let i = 0; i < list.length; i++) {
if (n < list[i][0]) {
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if (flat === true) {
return list[i][1]
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} else {
return this.pick([list[i][1]])
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}
}
n = n - list[i][0]
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}
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if (flat === true) {
return list[0][1]
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}
return this.pick([list[0][1]])
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},
weighted: function (wa) {
// More memory-hungry but hopefully faster than random.choose$flat
let a = []
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for (let i = 0; i < wa.length; ++i) {
for (let j = 0; j < wa[i].w; ++j) {
a.push(wa[i].v)
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}
}
return a
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},
use: function (obj) {
return this.bool() ? obj : ''
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},
shuffle: function (arr) {
let i = arr.length
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while (i--) {
let p = this.number(i + 1)
let t = arr[i]
arr[i] = arr[p]
arr[p] = t
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}
},
shuffled: function (arr) {
let newArray = arr.slice()
this.shuffle(newArray)
return newArray
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},
subset: function (list, limit) {
if (!(Array.isArray(list))) {
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logger.traceback()
throw new TypeError('random.subset() received a non-array type: \'' + list + '\'')
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}
if (typeof limit !== 'number') {
limit = this.number(list.length + 1)
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}
let result = []
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for (let i = 0; i < limit; i++) {
result.push(this.pick(list))
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}
return result
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},
pop: function (arr) {
// Removes and returns a random item from an array
let i, obj
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i = this.number(arr.length)
obj = arr[i]
arr.splice(i, 1)
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return obj
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},
hex: function (len) {
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return this.number(Math.pow(2, len * 4)).toString(16)
}
}